1. Field of the Invention
The present invention relates to an intake manifold for an engine and particularly, a method of securing intake tubes in an intake manifold.
2. Description of the Related Art
Intake manifolds for combining intake tubes to a multi-cylinder engine to groups or a single bundle are arranged to prevent interference between the intake tubes and to provide uniform distribution of intake air.
A known intake manifold 1 includes, as shown in FIG. 8, a collector 2 formed of aluminum die-casting, a plurality of intake tubes 3 made of aluminum pipe, and an intake tube mount 4 formed of aluminum die-casting for fixedly mounting the intake tubes 3 to the engine. The intake tubes 3 are inserted into intake tube mounting rings 5 formed on the collector 2 and the intake tube mount 4 as shown in FIG. 9 and fixedly joined to the intake tube mounting rings 5 by point welding such as spot welding at points A or A' on the periphery shown in FIG. 9.
In such a conventional method of securing the intake tubes 3 to the intake tube mounting rings 5, brazing in a furnace for jointing the intake tube mount 4 with the intake tube mounting rings 5 may produce a leakage of brazing material from the points A of spot welding between the intake tubes 3 and the intake tube mounting rings 5. Accordingly, an extra amendment for the brazing is needed and the leakage of brazing material runs out to a portion B of the intake tube mounting ring 5, thus resulting in loss of the brazing material. This may cause a sealing failure when the intake manifold 1 is installed in the engine. Also, the point welding such as spot welding may be likely to have the intake tubes 3 joined to the intake tube mounting rings 5 in tilted state as denoted by 3' in FIG. 9.